The invention is related to a solenoid valve for hydraulic brake units with slip control.
In the solenoid valves for hydraulic brake units with slip control for example as shown in German patent application published without examination, U.S. Pat. No. 3,739,915, special pressure limiting valves which are structurally separate from the traction slip control inlet solenoid valves are provided in order to limit the pump pressure to an established maximum value. Indeed, during the traction slip control action, the traction slip control solenoid valves which take the form of isolating valves and are arranged downstream of the master cylinder, are closed. Thus, upon start up of the auxiliary pressure pumps for the purpose of traction slip control action, the brakes of the driven wheels are subjected to the system pressure being monitored by the pressure limiting valves, a return of hydraulic fluid through the pressure limiting valves into the master cylinder being rendered possible only by the admissible pressure of the traction slip control system being exceeded.
The requirement of separate pressure limiting valves lead to an expensive brake unit and has thus proved disadvantageous.
The invention has, therefore, the object to further develop a compact solenoid valve whose number of component parts is minimized by integration of the pressure limiter function.